By clicking on the link below, you will find the Melbourne Groundwater Map, provided by Our Water.  It show approximate yields, salinity levels and depths of aquifers in the Melbourne and Mornington Peninsula areas.

Please note that this information is generalised and individual bores may vary in some areas.

Link to Melbourne Groundwater Map: 

http://www.ourwater.vic.gov.au/__data/assets/pdf_file/0020/53462/Melbourne_Groundwater_Map_HighRes.pdf